Arsenic levels in Waipā
UPDATE: 4 December 2024
Levels of arsenic in drinking water from all three treatment plants in Waipā have returned to below Drinking Water Standards maximum acceptable values.
Yesterday evening’s results recorded 0.0078 and 0.0097 milligrams per litre from the two main treatment plants, down from 0.01 and 0.011 on Monday, and the original results of 0.0138 and 0.0145.
The Alpha Street plant results were 0.0078 milligrams per litre yesterday, down from 0.0117 on Monday.
The maximum acceptable standard for arsenic in New Zealand drinking water is 0.01 milligrams per litre.
Water services manager Karl Pavlovich said while the level drop is great news, the council will continue to test daily to ensure any further variation is captured.
“We’ll continue with our enhanced arsenic monitoring plan for the next few weeks and will also review our regular monitoring programme.”
“We’d like to collect more data on both the source of the arsenic and how the effectiveness of our treatment can be improved,” Pavlovich said.
Waipā draws some of its water from the Waikato River, where naturally occurring arsenic levels are generated by geothermal activity and accumulated arsenic sediments within the hydro lakes along the river.
The Water Services Authority - Taumata Arowai and Health New Zealand have confirmed that drinking water with slightly elevated arsenic levels for a short period of time is unlikely to impact health. The limits in the New Zealand Drinking Water Standards are based on the level of risk from a lifetime of drinking the water.
Test results received
| Test Date | Karāpiro WTP | Parallel Road | Alpha Street WTP |
| 3 Dec 2024 | 0.0078 | 0.0097 | 0.0078 |
| 2 Dec 2024 | 0.0100 | 0.011 | 0.0117 |
| 1 Dec 2024 | 0.0135 | 0.0138 | 0.0131 |
| 30 Nov 2024 | 0.0112 | 0.013 | 0.0113 |
| 29 Nov 2024 | 0.0128 | 0.0131 | 0.0125 |
| 28 Nov 2024 | 0.0131 | 0.015 | 0.0131 |
| 27 Nov 2024 | 0.0138 | 0.0145 | Not tested |
- We have added the Alpha Street water treatment plant to the testing regime, to ensure it is up to standard when it comes into use over the summer period.
- 0.01mg/litre is the maximum acceptable value for Arsenic set under Water Services (Drinking Water Standards of New Zealand) Regulations 2022.
UPDATE: 29 November 2024
Update on arsenic levels in Waipā
Waipā water is still safe to use, with today’s test results showing a continued small reduction in the levels of arsenic in the district’s treated drinking water.
The results received this afternoon recorded 0.0128 and 0.0131 milligrams per litre from the two main treatment plants, down from 0.0129 and 0.0143 yesterday, and the original results of 0.0138 and 0.0145.
The maximum acceptable standard for arsenic in New Zealand drinking water is 0.01 milligrams per litre.
Water services manager Karl Pavlovich said the council has now added the Alpha Street water treatment plant to the testing regime, to ensure it is up to standard when it comes into use over the summer period. The Alpha Street plant results were 0.0125 milligrams per litre this afternoon, down from 0.0126 yesterday.
“We will continue to test daily,” Pavlovich said. “The water remains safe for drinking, bathing, and cleaning, and there is no need for people to boil it.”
The Water Services Authority - Taumata Arowai and Health New Zealand have confirmed that drinking water with slightly elevated arsenic levels for a short period of time is unlikely to impact health, while New Zealand Food Safety says the levels detected are not harmful to animals or to food production.
Waipā draws its water from the Waikato River, which has naturally-occurring arsenic levels generated by geothermal activity.
Testing is done by Hill Laboratories, Hamilton.
UPDATE: 28 November 2024
Waipā District Council’s water supply remains safe for drinking, bathing, and cleaning, following test results which showed small increases in the level of arsenic present.
Recent testing of water supplies drawn from the Waikato River has shown slightly elevated levels of arsenic.
Watercare and Hamilton City Council’s test results were identified earlier this week. As the levels exceeded limits set under Drinking Water Standards, the results were reported to the regulator, The Water Services Authority - Taumata Arowai.
We sampled our water treatment plants yesterday, Wednesday, November 28, and the results showed elevated levels of arsenic, which have been reported to the regulator, The Water Services Authority - Taumata Arowai.
Testing recorded results of 0.0138 and 0.0145 milligrams per litre from two Waipā water treatment plants. The increase exceeded the 0.01mg/litre maximum acceptable value for Arsenic set under Water Services (Drinking Water Standards of New Zealand) Regulations 2022.
The limits in the New Zealand Drinking Water Standards are based on the level of risk from a lifetime of drinking the water, meaning they are very conservative.
Boiling water before use is unnecessary and not recommended. While the risk is very low, if you have concerns, contact your GP or Healthline.
We are doing additional testing and taking the advice of The Water Services Authority - Taumata Arowai, the drinking water regulator, and Te Whatu Ora Health New Zealand.
Arsenic is a naturally occurring heavy metal found in the Waikato River. Some of it comes from the geothermal activity near Lake Taupo and other natural sources downstream.
Waipā gets its drinking water from the Waikato River, and it is thoroughly treated before it reaches our taps. Our treatment plants remove around 80 per cent of river water’s natural arsenic levels.
We are turning on additional processes used in summer to remove taste and odour issues, which will help reduce the arsenic levels.
The slight variation noted recently may be due to increasing natural levels.
What are we doing about it?
- We will continue to test daily to keep an eye on the situation
- We are turning on additional processes used in summer to address taste and odour issues, which will help reduce the arsenic levels.
- We are working closely with Waikato Regional Council, other government agencies, and local councils.
- We are seeking advice from subject matter experts to see if there is anything more we can do.
What are the health impacts?
- Health New Zealand and Taumata Arowai indicate the elevated levels, although a breach of the standards, do not present any immediate concern for public health.
- While the risk is extremely low, people who may be especially vulnerable, such as dialysis patients, pregnant people or babies, could use bottled water for drinking or cooking, and should contact their GP or Healthline if they have concerns.
- Drinking water with slightly elevated levels for a short period is unlikely to cause any health effects.
- The limits in the New Zealand Drinking Water Standards are based on the level of risk from a lifetime of drinking the water, meaning they are very conservative
What do we want you to do?
- While the risk is very low, if you have concerns, contact your GP or Healthline.
- High users of water for food-related products will need to consider the risks to compliance regarding export standards.
For information on harvesting watercress safely, download our marae food safety guide.
Media releases
- Joint release - Waikato River water suppliers achieve compliance
- Drinking water arsenic levels get the all-clear - 4 Dec
- Joint Media Release - Waikato River quality update - 29 Nov
- Update on arsenic levels in Waipā - 29 Nov
- Joint Media Release - Waikato River quality update - 28 Nov
- Waipā water safe to drink, increase of arsenic levels found - 28 Nov
